Fighting Reflective Rooms Through Speaker Placement Angles

[Max Warasila]

Bit of backstory first:
The deployment of speakers in our auditorium is painful. The QRx115/75 boxes are shown on the left about 12 feet above the front of the audience in the diagram below. It misses the first section of the auditorium, puts a ton of energy on the walls, and is so far separated L/R that about 25% of the audience is missed by the coverage as shown on the left in the picture below. Our auditorium is all wood, and reflects like crazy. Decay is about 2-4 seconds by my ear estimation, and mostly in the highs as one would expect.


Here's my question: can I combat the reflections by stacking the speakers (or another set-up with about 80-100 degrees of nominal H-dispersion) on the stage instead? More importantly: is this even a remotely good idea? Another option I was considering was hanging a VRX array with 1 sub and two 932s below it (since I can borrow that from central county equipment if I ask nicely).

To clarify, the objective is to reduce reflections off the wall (to improve clarity), get more consistent coverage in terms of frequency response (more than even volume), avoid overshooting the audience and hitting the back wall (like the current deployment), and just make it sound better than what is already there.


I don't know… this really isn't my strong suit, as I've always been more of a mixer person than sys-tech. I'm open to ideas, and I have at least a little bit of money at my disposal for rentals/additional gear, as well as a bit of gear I might be able to get my hands on through central county equipment.

Additional Info Added Through Edits:
-I can't change the install; it's all temporary for the run of a particular show
-Anything that I change I have to put back

One other question I have is if it is a BAD idea to angle speakers/arrays in towards the center of the room/space/audience, and why/why not.

 

[Evan F. Hunter]

Re: Fighting Reflective Rooms Through Speaker Placement Angles

I am thinking that with those two speakers you will never 100% cover the room. However since you have a little budget, why not call an install company and have them properly aimed and flown and/or talk about system changes or upgrades? Fly them more "infront" to the left and right of the stage, pointed best to cover crowd and aimed down accordingly to how deep the room is and coverage. Possibly add some delays after that..... You could stack/pole mount on stage for similar results, but I find that in a multipurpose auditorium they get knocked and moved and "in the way" of other stuffs.

 

[Max Warasila]

Re: Fighting Reflective Rooms Through Speaker Placement Angles

I am thinking that with those two speakers you will never 100% cover the room. However since you have a little budget, why not call an install company and have them properly aimed and flown and/or talk about system changes or upgrades? Fly them more "infront" to the left and right of the stage, pointed best to cover crowd and aimed down accordingly to how deep the room is and coverage. Possibly add some delays after that..... You could stack/pole mount on stage for similar results, but I find that in a multipurpose auditorium they get knocked and moved and "in the way" of other stuffs.

You're right- there's no chance in hell I can cover the entire room. But I can get most of it. It's a school system, so I can't get the install "redone" easy, but I can change things for one show. I've always wanted them to be flown the way you are suggesting, but it's not likely to happen. I'll add into the OP that it's temporary.

 

[Evan F. Hunter]

Re: Fighting Reflective Rooms Through Speaker Placement Angles

You're right- there's no chance in hell I can cover the entire room. But I can get most of it. It's a school system, so I can't get the install "redone" easy, but I can change things for one show. I've always wanted them to be flown the way you are suggesting, but it's not likely to happen. I'll add into the OP that it's temporary.

I understand how hard it is to get stuff done in schools and such. However a good company can take and put up new fly points, run longer wire and have them aimed/tuned in the same day. 1 day labor and materials could be doable if the school is at all interested in fixing it. I do this nearly once a week now since ive picked up an install job. I own some QRX115s myself and they are great speakers, however a single pair doesnt offer much coverage in larger spaces.

 

[Max Warasila]

Re: Fighting Reflective Rooms Through Speaker Placement Angles

I understand how hard it is to get stuff done in schools and such. However a good company can take and put up new fly points, run longer wire and have them aimed/tuned in the same day. 1 day labor and materials could be doable if the school is at all interested in fixing it. I do this nearly once a week now since ive picked up an install job. I own some QRX115s myself and they are great speakers, however a single pair doesnt offer much coverage in larger spaces.

The school isn't interested, and to be honest, there's a whole bunch of "standards" that we have to follow in our installs that make it pretty much impossible to get a good system in there. Hence, I'm focusing on all temporary stuff. It's a harder room, though it seems simple at first. The reality is that it is a 92 foot deep house with only a floor at a 3-6 degree grade, and a ceiling height of 20' descending to 18' by the back of the room. Every surface, minus the floor, is reflective- and highly at that. It's a nightmare, and the only installs that the county will do nowadays is to put two JBL speakers (usually Control 29s, Control 30s, or sometimes Applied Engineering series stuff, if they feel generous) on the proscenium (!) in their brackets. They refuse to fly anything, and the last time I checked the wiring it's usually 100+ feet of 18ga. to the speakers. I've basically given up on the install approach.

Not to mention that even if they did agree to do the install, it would take 3 weeks because of the "system" to get it approved, checked, and actually put in. A new install of 36 S4LEDs on 4 trusses took about… 3-4 weeks plus inspection? Granted they had to tear out the conventionals, but it was ridiculous! They spent 3 days removing an electric…

Bottom line, I'm looking for temporary solutions, as much as I'd love to have a good install. I really do appreciate the encouragement to get a good install in there.

 

[Dirk Martens]

Re: Fighting Reflective Rooms Through Speaker Placement Angles

Fly them in the middle above the stage pointing down. Makes it mono but should exit the room less.

 

[Tim McCulloch]

Re: Fighting Reflective Rooms Through Speaker Placement Angles

I understand how hard it is to get stuff done in schools and such. However a good company can take and put up new fly points, run longer wire and have them aimed/tuned in the same day. 1 day labor and materials could be doable if the school is at all interested in fixing it. I do this nearly once a week now since ive picked up an install job. I own some QRX115s myself and they are great speakers, however a single pair doesnt offer much coverage in larger spaces.

Schools (public and many private) won't replace rotting curtains. Schools will wait to repair weak boards in the stage floor until someone or something falls through, then they're more likely to close the stage than fix it. Why? They don't have the money.

Auditoriums get a refresh about once every 30 years. They need it every 15. A meaningful rebuild comes every 60-80 years. Both require a population that is willing to pay for the fixes, and that is too often lacking.

Just based on what I've seen over the last 40 years...

 

[Max Warasila]

Re: Fighting Reflective Rooms Through Speaker Placement Angles

Schools (public and many private) won't replace rotting curtains. Schools will wait to repair weak boards in the stage floor until someone or something falls through, then they're more likely to close the stage than fix it. Why? They don't have the money.

Auditoriums get a refresh about once every 30 years. They need it every 15. A meaningful rebuild comes every 60-80 years. Both require a population that is willing to pay for the fixes, and that is too often lacking.

Just based on what I've seen over the last 40 years...

Tim's totally right. Especially on the meaningful rebuilt part: our auditorium needed to be renovated (refurbished, etc) about… oh a few years ago now. We are on the renovation list for 203…2 is it now? Point is that by that time, renovating it will make it worse. And with what they have been doing to most of the renovated auditoriums, I'm not even sure I want that.

I do want new welds on a few of our catwalk rails. I do not, however, want a sheetrock doomsday in the house.

The issue of not having money isn't even as much of the issue. It's that they didn't spend the money on good builds, so they break faster and cost even MORE later. Which sucks, especially on some… scarier… renovations.

Oh, and Tim- congrats on 2k posts. You're now a "Post Doc," I see.

 

[Ivan Beaver]

Re: Fighting Reflective Rooms Through Speaker Placement Angles

Remember it takes SIZE to control the pattern of a loudspeaker-at least down to anything low enough to start to make a difference.

With a small horn-the control is limited to the higher freq. NOT across the freq range the cabinet is being used for.

Simple physics and there is no way around it-sorry.

You may be able to reaim them a bit for better coverage-but you will have to decide what seats are more important than others.

If the system is not covering the room properly-it is yet another example of people who simply have no clue what they are doing-and the customer accepting the job and paying them-allowing them to do yet another job wrong.

Truly sad the number of people who call themselves "professionals" in this business.

The COVERAGE needs to the be PRIMARY thing in any sound system design. Everything else comes later. It doesn't matter how good a particular loudspeakers sounds-if everybody can't hear it-----------------

But that doesn't stop people. Many times I am embarrassed to be associated with some people in our industry.

 

[Brian Bolly]

Re: Fighting Reflective Rooms Through Speaker Placement Angles

So can you move the current speakers, even if only temporarily? Why not rehang/reaim the current speakers in a center cluster configuration? Horns may need to be rotated, and you are still going to get some reflections off the walls, but simple physics dictates that by reducing the number of sources you will reduce the number of reflections.

Front fills would still be a good idea, even if only to bring the imaging down in the front. (Does the central equipment pool have any of those Control29s laying around?)

It appears that the original "designer" (and I use that term loosely) attempted a "stereo" installation in this room. Given the acoustical challenges, and the scaling challenges of stereo (see Bob McCarthy's blog here for a much more in-depth explanation), you would be better off with a mono center cluster application. They still may be the wrong speakers for the job, but with little to no budget you play the cards you're dealt.

Also - any extra pipe and drape laying around? Even schools sometimes have a couple extra hampers of drape that could be useful.

 

[Rob Timmerman]

Re: Fighting Reflective Rooms Through Speaker Placement Angles

How are the current boxes mounted? If they are in brackets, can you simply rotate them in further to get more coverage up front and less energy directly into the side walls?

 

[Max Warasila]

Re: Fighting Reflective Rooms Through Speaker Placement Angles

How are the current boxes mounted? If they are in brackets, can you simply rotate them in further to get more coverage up front and less energy directly into the side walls?

Actually, they are on shelves, and their height prevents them from hitting the first 2-6 rows well, or the first 20 I'm not sure why they were put on those shelves, but I digress.

Ivan, considering that the really frustrating reverberation in the room is about 800-6k, I'll take what I can get from an average horn this time. I'd love to have a pair of Danley SHs in there, but that IS a bit out of budget… at least install wise. ~:-D~:grin:

The problem with the center cluster is two things: first, the coverage of those will drop the corner seats, and second, will throw a ton of sound on the left/right walls from that height. Actually, I lied. There's a third: it's in the way of the lights from the catwalk. (See attached CAD sketch) The catwalk is another sob story, but this is a sound forum. Might be able to hang from a point just in front of the catwalk and drop it below. Then we run into a lack of front/back coverage. Hm. I'm assuming that's what you meant by horn rotation. If they let me do it, it might work.
I'll add that to the pile of suggestions. Thanks Brian!

Another option that's forming in my mind (if I can't rotate the horns) is to hang them horizontally. The L-tracks will work better for that anyway, I think. In the event that I do, should I hang them with the 15s on the inside or outside? Outside, right? Or inside? Maybe I'll just run the math. That's always a start.

One last thing I'd like to bring up is that we're likely going to use all tracks for this production, so no live pit orchestra. I'll end up having to provide monitors, and for an apron that size, I was thinking that the two 115s could be disguised in scenery about where I was suggesting the stack be, acting as a sort of side fills. The install monitors are behind the proscenium and stuck behind the thick curtain of the legs (great install, once again…).

 

[Ivan Beaver]

Re: Fighting Reflective Rooms Through Speaker Placement Angles

Ivan, considering that the really frustrating reverberation in the room is about 800-6k, I'll take what I can get from an average horn this time. I'd love to have a pair of Danley SHs in there, but that IS a bit out of budget… at least install wise. ~:-D~:grin:

.

What I was pointing out is a mistake that many people make-assuming that the rated horn pattern ACTUALLY controls the sound in that pattern down into the "meat" of the sound. In most cases it does not.

Also starting with a pair of cabinets is a bad idea-especially for a reverberant space.

Unless the customer is insisting on stereo (and has the budget to do it right) I ALWAYS start with a SINGLE loudspeaker in the middle. Then possibly add some small fills if needed-exploded out to the left and right-NOT located with the main speaker.

That is called LOUDSPEAKER SYSTEM DESIGN-NOT "Let's put these speakers up and hope for the best" based on no knowledge of how they would ACTUALLY work in the particular space.

But sadly most sound systems have no real thought or design (although the people putting them would argue differently) put into them-at least on how well they will cover the intended space.

In SOOOOOO many cases-as long as the system makes some kind of "noise" the "designer" is happy

I am hoping for the day in which STIPA measurements become law-and building cannot open until the system meets certain criteria.

At least a lot of the guys who are doing poor quality will go out of business due to trying to fix it or lawsuits.

But I feel that is a bit away-but is a good start for a minimum system REQUIREMENT-of which there is none now.